The present invention relates generally to systems, apparatus and methods for the production of finger jointed dimensioned lumber, molding stock, poles and beams produced from sawmill green rough trim.
The United States (U.S.) has substantial timber forests as a source of logs for the production of forest products such as paper, dimensional boards, sheets boards, poles, beams and pressed formed wood fiber products. Though the number of U.S. forest acres have been reduced by 50% over the past 200 years, logs are now harvested on a rotational basis providing a sustainable supply of timber. Furthermore, production facilities continually optimize their wood fiber usage which is typically the most expensive component of their product.
As an example, the production of dimensional lumber is a sequential process starting with de-limbed green logs and ending with stacks of dried boards having width, length and thickness dimensions. The sequential process usually comprises the following steps:                Log bucking (cutting the tree length logs into saw length);        Primary breakdown of the saw log;        Secondary breakdown of the rough cants, fitches, and boards;        Length trimming of the green boards;        Collating, stacking, and drying of like-sized green boards;        Surface finishing (planing or molding) of the dry rough boards;        Length trimming of the finished dried boards;        Collating and stacking for commercial distribution.These sequential steps are common whether the lumber facility is a small single band mill or a high volume multi-primary breakdown facility. The processing of cylindrical poles (as utility poles, for example) and wooden beams utilize similar processes.        
One type of forest product high volume production mill is a chip and saw (“CNS”) facility. A CNS facility produces dimensional lumber from timber that has a diameter ranging from mid-sized to small. The CNS production concept was developed to produce higher value dimensional lumber while providing a source of white chips for paper production using the smaller diameter logs. A typical CNS facility generates an average of more than five-hundred tons of dry biomass byproducts per day. (According to Marks Mechanical Engineering Handbook, the standard for “dry” is defined as twelve percent moisture content or less.) These biomass byproducts typically comprise white chips, bark, sawdust, and wood shavings. The white chips produced by a CNS facility are sold to paper-producing mills for processing into paper and cellulose products. The bark, sawdust and shavings are either used at the CNS facility as a thermal energy source or sold as lower value byproducts. While manufacturing dimensional lumber, a CNS facility will also produce green rough trim blocks having a moisture content of over 40% as well as dry trim blocks with moisture content under 20%. According to Southern Pine Inspection Bureau (“SPIB”) guidelines, construction grade lumber two inches thick with a moisture of 19% is known as KD19.
Green rough trim blocks are chipped and added to the white chips that are sold to the paper production industry or to post mill processing facilities such as pellet manufacturers. The production plant continually optimizes the log bucking and primary breakdown to minimize the number and amount of green rough trim blocks produced due to their lower value. CNS production mills currently produce approximately 14% of their production volume as green rough trim blocks. Approximately 40% of the green rough trim blocks can be converted into finger jointed dimensional lumber while approximately 20% of the green rough trim blocks can be converted into finger jointed molding blocks used to manufacture molding trim.
The dry trim blocks are ground into fuel for direct fired drying kiln or sold as low value stock for additional processing such as pallet components; truss web; or finger jointed dimensional lumber. Finger jointed lumber manufactured from dry finished trim blocks typically does not have sufficient fiber for finishing into dimensional lumber following the finger jointing process. The resulting boards have undesirable steps and offsets at the finger joints and inferior joints due to the insufficient material prior to the finger jointing process.
The production of dimensional lumber follows industry grading rules such as those promulgated by the SPIB. These rules provide the following minimum allowances for thickness, width, and length of the finished products:                Thickness: based on a quarter system expressed as four quarter, (one inch); five quarter, (one and one quarter); eight quarter, (two inches), etc.;        Width: based on two inch increments starting with a four; six; eight; ten; and twelve; and        Length: based on two foot increments; six; eight; ten; twelve; fourteen; sixteen; eighteen and twenty.All finished dimensions are based on dry lumber; therefore, the production mill must allow for shrinkage due to drying and other process variables. Thickness and width are fractional inch increases while the length increase is in inches. Following primary and secondary breakdown, the green lumber is trimmed, for example, on two foot lengths. In the past, the resulting green rough trim blocks have been collected and chipped into white chips at a commodity value. Processing the green rough trim blocks into finger jointed dimensional lumber and finger jointed molding blocks can increase their utility and value.        
An issue with the production of kiln dried lumber is the defects incurred during the drying process. Warping, checking, splitting, and case hardening all reduce the amount of dried rough boards available for finishing into dimensioned lumber for market.
What is needed is a system, method and apparatus to utilize green rough trim blocks for production of high quality finished finger jointed dimensional lumber and molding stock.